This has only happened to me once, on heavy doses of DXM & 4-AcO-DMT together.
I was out of body for much of it as well, no real concept of self, drugs, or anything but what I was experiencing, though the moments where I was in my body I had some awareness of my self & recognized my room, was able to do things like use the bathroom & drink a little water.
The place I went to for much of the experience felt like somewhere I'd been before even though I hadn't. I remember when I was already quite high on the DXM & coming up on the 4AD thinking things like "oh this again", "this happens every time", "why do I always forget this part?", as well as briefly thinking I'd taken it a step too far and was dying of serotonin syndrome.
This is also the only time I've left my body, even very high smoked/vaped DMT doses which had me feeling like I'd entered the spirit world, and quite insane, otherworldly, mystical visuals, but it all grew out of the pre-existing world, and I was still firmly in my body, though about the most fried I've been on psychedelics.